The invention pertains to flexible and elastic pipes or hoses, the rubber walls of which are reinforced by at least plies or two pairs of plies reinforced with flexible metal cables arranged in a coil; these hoses are fixed, at least at one end, to rigid closing or connection pieces. The invention pertains, more particularly, to devices of the type which comprises a flexible hose which can expand under internal pressure to form an inflatable plug which serves to block conduits to be repaired, wells or other similar applications. For certain uses, for example to block large-diameter conduits such as pipelines or oil wells, it must be possible to inflate the device at very high pressures, which may reach several hundred bars, in order to ensure the tightness of the seal and to resist the axial expulsion force to which it is subjected by the differential pressure between the upstream and downstream sides of the conduit. The severity of these operating conditions poses difficult problems in ensuring satisfactory attachment of the ends of the hoses to the rigid pieces.
For devices of relatively small diameter, i.e., up to 150 to 200 mm, it has been possible to use at the rigid end pieces dummy connectors of the type in which the end of the hose or of its reinforcing plies which are previously stripped bare is locked radially between an inner tip and an outer bushing; the tip and bushing are tubular, coaxial and essentially cylindrical.
For larger diameters and/or for higher pressures, it would be possible to use systems of rigid annular flanges of the type used to connect large-diameter flexible hoses. These annular flanges have the drawback, however, of having an outer diameter which significantly exceeds the diameter of the hose; this is particularly problematical in the case of an inflatable stop plug which must be put into place through poor accesses or is likely to have to pass through bent sections of the pipe or conduit. In addition, these flanges greatly reduce the useful expansion capacity of the hose since the only thing accomplished by the first part of the radial expansion of the hose is to bring this hose up to the diameter of the flanges, and only the expansion of the hose after this point in time can make it possible to push the hose firmly against the inner surface of the conduit to be plugged.
Consequently, the invention is aimed at providing a flexible hose device in which the ends of the hose are attached extremely firmly to rigid end pieces in order to allow the entire assembly to resist very significant forces, especially those resulting from very high pressures.